This invention relates generally to a method and apparatus for land mobile radio products, and more particularly, to a method and apparatus for signaling on conventional analog FM systems or trunked analog FM systems.
Some prior art analog FM transceiver systems utilize one of two known methods to implement digital signaling (e.g., MDC-1200 signaling) on analog FM transmissions. The first of these methods uses specialized circuitry and software built into the transceiver for transmitting MDC-1200 signaling. The second of these methods uses an off-the-shelf MDC-1200 encoder module inserted within the analog-FM transceiver. Often these transceivers require modifications, changes, rework, or optional slots and positions, to accommodate the modules.
The first method uses specialized circuitry and software built into the transceiver for transmitting MDC-1200 signaling. This method can be costly and is not easily retrofitted into existing transceiver systems. In some cases, entire radio systems may have to be replaced to maintain compatibility between radios and/or base stations.
The second method uses an off-the-shelf MDC-1200 encoder module applied inside the analog-FM transceiver. Often these transceivers require modifications, changes, rework, or optional slots and positions, to accommodate the modules. Thus, these methods for implementing digital signaling can also be costly and may not be easily retrofitted into existing radios.